A fight that started on Facebook ended in bloodshed when a 22-year-old was stabbed to death in a Brooklyn housing project after an argument over $20 she lent her boyfriend’s sister for diapers, authorities said.

Kamisha Richards was attacked Monday at 10:35 p.m. near her home at the Cypress Hills Houses on Sutter Ave. in East New York, police said.

She was stabbed once in the chest, police said.

Richards was taken to Brookdale Hospital, where she was pronounced dead a short time later.

Police later caught the suspect Kayla Henriques, 18, who is the mother of an 11-month-old boy and lives in the same housing complex as the victim.

On Sunday night, Richards and Henriques had gotten into a heated war-of-words on Facebook.

In one message, Richards wrote: “I don’t give a f–k. … U know ya sister so its not just ova $20 its the principle so don’t make it seem like I’m goin n 4 $20 she kno wat she did and she real f–ked up … this aint the 1st time she did dum sh-t…F–K THESE NOSY PPL!!!!

In response, Henriques threatened Richards.

“Dnt try to expose me mama but I’m not tha type to thug it ova facebook see u wen u get frm wrk,” she wrote.

Henriques was arrested this morning and has been charged with second-degree murder.

A friend of both women said Henriques always needed help.

“The day before yesterday she came to me looking for some pampers,” she said. “She was always low on stuff. Kamisha used to help out with the baby and used to baby-sit. She was even helping to plan the baby’s birthday party in May.”

The friend, who did not want to be named, also said Richards “didn’t like people who took advantage of her.